Method of curing green tobacco



March 7, 1944. R. D. TOUTON METHOD oF CURING GREEN' lToAcco 3sheets-sheet 1 Filed Dec. 1l, 1940 r rmrrr fd WEA/raf? /zPas/ 73u for:

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METHOD OF CURING GREEN TOBACCO Filed Dec. l1, 1940 3 Sheets-Sheet 2RAD/A raf? V Mum/fas.' @Wr/M( March 7, 1944. n R. D, TQUTON 2,343,345

METHOD Of CURING GREEN TOBACCO Filed Deo. l1, 1940 3 Sheets-Sheet 3Patented Mar. 7, 1944 METHOD OF CURING GREEN TOBACCO Rush D. Tonton,Cynwyd, Pa., assignor to Wurton Machine Company, Philadelphia, Pa., acorporation cf Pennsylvania Application December 11, 1940, Serial No.369,652

(Cl. ISL-140) 17 Claims.

This invention relates to a method for curing green tobacco and moreparticularly relates to a method adapted for the curing of green tobaccoin the eld following its harvesting. The apparatus disclosed herein foruse in performing said method is also disclosed in my copendingapplication #369,653 filed Dec. 11, 1940.

As is well known, green tobacco leaves after harvesting have heretoforebeen strung closely inl pairs and hung in banks in a dense mass forcuring in so-called sheds, having a tight roof and walls formed bylouvers capable of adjustment for various openings.

The curing of the green tobacco leaves in the sheds requires about days,more or less, 'and it has been sought to obtain desired atmosphericconditions; i. e., temperature and moisture content, within the sheds byvarious adjustment of the louvers and the burning of charcoal potswithin the sheds with respect to the prevailing temperature and moisturecontent of the outside atmosphere, the wind velocity and its directionwith respect to the sheds.

However, it has been found that the closeness or dense packing of theleaves as they are hung in the shed results in unsatisfactory curing ofthe leaves near the walls of the shed and insulation of the inner leavestoward the center of the shed so that they do not receive propertreatment. This insulation of the inner leaves is particularlyobjectionable while the leaves are still green, starchy and distended totheir full face area and at the same time contain a maximum watercontent.

It has also been found that non-uniformity in the curing of the tobaccoin any given shed arises from the fact that curing of the tobacco in theupper part of the shed, which is placed iirst, starts and often proceedssubstantially before curing of the tobacco in the lower part of theshed, placed last, starts.

Further, under present practice and with present equipment it isextremely dicult, if not impossible, to maintain the necessaryconditions for good curing during the latter stages of the operation, asfor instance, after the sixth to seventh day, due to the shrinking ofthe leaves which permits too great a circulation of dry air, together.with the fact that the leaves no longer contain suiiicient moisture tocreate the necessary relative humidity.

The present procedure, essentially dependent upon general atmosphericconditions, of necessity is lacking in any uniform control of theconditions under which the tobacco is cured,

makes no allowance for the different characteristics of different partsof the tobacco leaf and frequently results in the production of tobaccoof low quality, from the standpoint of texture, color and taste, andconsequently of a value considerably less than could be expected fromthe nature of the green tobacco when harvested.

A careful study of the nature of the green tobacco leaf and of therequirements of proper curing shows that the butt and stem portions ofthe leaf are relatively coarse and sappy and contain a relatively largeamount of moisture, while the median portion, containing less moisturethan the butt and stem, contains substantially more moisture and iscoarser than the relatively fragile tip portion. Furthermore, themaximum width of the leaves occurs in this median portion setting up anoverlapping condition with a resultant impedance of circulation when theleaves are placed in the curing shed.

In the curing of the green tobacco leaf, it is the object to remove themoisture, to the desired extent, and bring the leaf to desired color,while, at the same time, retaining its texture. In general, it is usualto support in the average shed about 40,000 pounds of green tobaccoleaves, of

which weight some is moisture. In the curing, the tobacco leaves arebrought down to a weight of about 10,000 pounds, of which some 20% ismoisture. In the curing the major moisture loss occurs in the rst fiveto six days and care must be exercised, especially between the secondand sixth days, to avoid rotting or pole sweat which is most likely tooccur in the median portion of the leaf, when the leaf has partiallywilted and part of the leaf cells are dead, but the leaf still containsfrom 50% to 70% moisture, which promotes the growth of pole sweat sporesin the dead cells.

In the prior practice indicated above, as will be obvious, the tobaccoleaves were essentially subjected to atmospheric air, the humidity,temperature and flow of which was subjected to variation with thephysical condition of the leaves, time of day or night and localmeteorological conditions under such control only as could be exercisedby adjustment oi the louvers forming the sides of sheds and the burningof charcoal potswithin the sheds; and, again, the dense packing o'f theleaves prevented any approach to uniform circulation through the mass oftobacco. Also, the necessity for wide open louvers to admit suicient airfor anything like circulation in the center of the mass often causeswind damage on the leaves near the outside of the shed near the openlouvers ny event, subjects the outside leeres to ov; r"tic treatment incornparison with that by the inside leaves.

As a result of the noir-uniform condition of the atmospheric airavailable to the shed and the inecient control thereof, especially olthe volume and of its flow with respect to the tobacco leaves and thedifferent parts thereof, wide variation the conditions occurred locallywithin the shed from the effect of the rying tobacco upon the air.

Now in accordance with this invention there is provided a highly ecientand economical methor for the curing of green tobacco, and by thepractice and use of which the curing ofn green tobacco in the usual shedis enabled and production of tobacco of high quality is assured.

Generally speaking, in accordance with this invention green tobaccoleaves o-r plants are strung and hung in close relation as heretoforeconventionalA in a curing shed of the usual type having louvers in itswalls and modified only by provision for ventilation through the roof.Uniformly conditioned air or atmospheric air tempered with conditionedair to a uniform condition is introduced to the tobacco in controlledvolume and directionr of ilowfwith respect to the leaves and also withrespect to outside conditions, such as temperature and humidity andkwind direction and velocity, so that the different parts of the leavesare subjected to air at a condition and in circulation best suited totheir curing at a proper rate, with uniformity, with avoidance ofrotting and with retention of texture and ilavor and acquisitionofdesired color.

More specifically the conditioned air is introduced centrally of themass of tobacco and cir-V culated outwardly and downwardly therethrough.The airis variously introduced in quantity to create a positive pressurewithinV the shed and is introduced variously in greater quantity in thelower-part of, the shed than in the upper part and vice versa. Again,stackl effect in the shed by virtue ofY ventilation through thek roof,which may be enhanced by the introduction of air selectively into thelower part of the shed, or by heat from the surface of ducts throughwhich warm air is introduced, isused to promote uniformity. Again,downdrafteect may be obtained, causing an inilow; of air through theventilator desirable for the introduction of cool, normal night air totobacco` in the upper part ofthe shed by the introduction, of' cool airselectively in the upper part or the shed, or from the effect of thecool surface of ducts through which cool air is introduced intothe shed.

The circulation rate will vary from one complete change in ten minutesdownward to one change in forty minutes. Furthermore, during the laterstages of curing, for instance, after the fourth or fifth day, a greaterquantity of air :may be admittedat the bottom of the shed than at thetop while utilizing stack eiect. Again, intermittent operation orf thecirculating system may be desirable, asfor instance, for a total periodof not over lzhours in each 24. This may bei arranged for sixV hourscirculation during the day' and six at night with the night operationbeing particularly? important during the early morning hours when thetemperature of the ground, shed and tobacco has been lowered to the dewpoint of the outsider air, thus causingy condensationV on the tobacco.

In addition, moisture from conditioning equipmentvmay be added to theatmospheric moisture as at night to provide the essential factor incuring known as come and go. That is, the conditioning system will beused in conjunction with the outside air. Generally, the conditionerwill be so arranged that it will add not more than 30% relative humidityto the air being crculated and if used for heating or cooling thetemperature increase or decrease over the outside air or that in theshed will be not over 15 F. These restricted increments will effectivelyprevent severe treatment of leaves next to the outlets as compared tothe present system where harsh conditions are imposed upon the tobacconear the outside walls and in the lower tiers directly over the charcoalreswhen such are used.

They conditioning system will be arranged so that during periods ofmaximum heat requirementk as when the shed is initially loaded withcold,A wet tobacco, additional outlets in the bottoms of the down draftducts will automatically open, thus providing the greater amount, of airnecessary to carry the required number of heat` units without adetrimental increase in the amount necessary in each unit of`circulating air.

Also, the central portion heretofore insulated from the proper heatingeffect and in a stagnant air condition will receive an adequatecirculation of conditioned air.

Furthermore, the air flow may be directed.

against the prevailing wind to establish further uniformity within thestructure and the outlets will be arranged for rotation so that they maybe variously directed under Acertain conditions to avoid any constantsevere treatment of leaves nexttothe openings.

Thisy application of conditioned air will be accomplished with mucheconomy, permitting the use of 'a standard curing shed structure sincethe conditioning efect is applied in the center ofthe mass desirablytocreate a positive pressure within the; shed, and in passing` outwardrthrough the leaves permits maximum service before its eilect isdissipated.

Having now indicated in a general way` the nature and purpose of themethod according to this invention, it is believed that it willbeunderstood in detailzfrom thefollowing description of a form ofapparatus-adapted for use in carrying out the method, with referencey tothe accompanying drawings in which:

Figure i is a plan view showing an embodiment of apparatus adapted forcarrying out the method in accordance with this invention.

Figure 2 is a diagrammatic sectional view of apparatus adapted forcarrying out the method in accordance with this inventiom taken adjacenta point of introduction of conditioned air into the mass of tobacco.

Figure 3v is a cross-,sectional View showing details or the airconditioning instrumentalities included in. the apparatus shown inFigures l andv 2.

Figure 'i is a detailed view, partly in section,

showingthe instrumentalities included in the a t for paratus inassociation with the wall of a tobacco curing shed.

Figure 8 is a side view of the air conditioning apparatus shown inFigure 7.

Figure 9 is a side View of a. string of tobacco leaves as hung in atobacco curing shed.

Figure 10 is a sectional view on line lil-I5, Figure 6.

Figure 1l is a view, partly in section, showing a detail ofconstruction.

Referring initially more particularly to Figure 9, I6 indicates a stringupon which. are threaded or strung a series of green tobacco leaves 7'.-The string I6 passes through the butts of the leaves and the leaves, asis customary, are strung in pairs I'I, the leaves of the pairs facingoppositely. In similar manner stalks may be hung. The string I5 issecured at its ends to a stick 7c adapted to be supported in the shed onrack members I8.

The tobacco leaves i are divided into three essential portions, asillustrated in Figure 9,

namely, the butt portion I9, the median portion 20 and the tip portion2i.

Referring now more particularly to Figures 1 5, A indicates a tobaccoshed, which may be of any desired size and construction7 and desirablywill have louvers a. in its walls. The shed will be located in anyconvenient position to the tobacco fields. A ventilator or series ofventilators 62, controlled by a damper S3, are provided in the roof ofthe shed to afford a stack eiect where desired.

B` indicates a tractor or any ordinary or desired type. The tractor maybe and desirably will be such tractor as may be used in connection withthe growing of tobacco to be ultimately cured in the shed A.

C is a trailer unit adapted to be coupled to and drawn from place topla-ce by the tractor B. Upon the trailer unit is an air conditioningapparatus or instrumentalities for the conditioning of air.

Within the lower part of the shed A and eX- tending longitudinally ofthe center thereof is an air duct E, provided on its upper side with aseries of upwardly directed nozzles f. The nozzles f are extended fromend to end of the duct E and are spaced suiliciently close so thatstreams of air g issuing from the nozzles will blend and travel upwardlyand outwardly within the shed, in and from a free zone mil between orcentrally of the banks of tobacco leaves, as will appear. Beneath theridge of the roof of the shed A and extending in a line above thenozzles f in duct E is a curved baiile li, divided centrally by averticalv member i. The member i is directly in line with the nozzles fand adapted to divide air traveling in zone 493 therefrom when itreaches the baffle.

As will be obvious from an inspection of Figure 2, the blended streamsof air g from the nozzles f passing upwardly within the shed A, in azone lill) extending vertically of the mass of tobacco supported onstacks ic in which the air is desirably at a positive pressure, willextend outwardly into the mass of tobacco and such as reaches the baffleli will be divided by the member i and directed oppositely downwardly bythe curved bafiie h so that a downward circulation of air will be set upwithin the shed, as indicated by the arrows Figure 2. By virtue of thedirection of the'circuiation the air directed downwardly will iirst passdownwardly along the butts of the leaves and then along the medianportions and then along the tip portions.

Leading from the duct E, a lateral duct M aligns with an opening n inthe side of the shed. Adjacent the opening n with which the duct Mcommunicates is an opening o in the side of the shed.

The air conditioning instrumentalities mounted upon the trailer Ccomprised, as shown in Figure 3, an intake duct p adapted to be alignedwith the opening o in the side of the shed and provided with a flange qadapted to bear against the side of the shed and make a tight connectionand a discharge duct 7', adapted to connect with i the opening n in theside of the shed with which the lateral duct M extending from the duct Ecommunicates. The end of the discharge duct is provided with a ange s(Fig. 4) adapted to bear against the side of the shed and make a tightconnection. The intake duct p is provided with an opening to theatmosphere t, controlled by means of a swinging closure u.

Within the intake duct is a coil v, the ends of which are adapted to beconnected with thv:r

water jacket of the tractor engine w through the medium of flexiblepipes or hose rc, 1: connected to nipples y, y, let into the walls ofthe water jacket and provided with valves e, e. A pump I, is providedfor effecting circulation of water from the tractor engine Water jacketthrough the coil y, with return to the water jacket.

Within the discharge duct is a pan 2 containing a coil 3 and adapted tocontain water to a level 4 to cover the coil 3. The coil 3 is connectedat one end through a exible pipe 5 to a nipple 6, which extends from theexhaust manifold 'l of the tractor engine and is provided with a valve8. The other end of the coil 3 leads to atmosphere, or preferably into apit (not shown) adapted to absorb exhaust gases. The end of the coilconnected to nipple 6 is provided with a valve I5 adapted to throttleand control the amount of exhaust gases passing from the engine manifold'I into the coil.

As will be obvious, when exhaust gases are permitted to circulatethrough the coil 3, which is beneath the water level 4 of the water inthe pan 2, water will be evaporated into the air passing through thedischarge duct and over the pan.

A fan 9 is provided in the discharge duct adjacent its juncture with thelateral M within the shed. The fan is adapted to be driven from thepower take-olf I0 of the tractor through the medium of a belt II. Thefan is arranged to operate to draw air from within the shed into theintake duct in heat interchange relation with coil v, then over the pan2 and discharge it into the lateral M, through which it passes toconduit E, from which it passes into the shed, as

fjdescribed above, through the nozzles f. The fan also serves to drawinto the intake conduit fresh air through the fresh air opening t. Thefan 9 may be reversed to reverse the direction of oirculation which mayvariously be desirable.

Within the shed is positioned a thermostat I2. which operates to controlthe circulation of heating fluid through the coil o through control ofthe operation of the pump l. The control of the pump Z by the thermostatmay be of any suitable or well known type, the control connections beingindicated by the line I3.

A humidostat I4 is positioned within the shed and operates to controlthe circulation of exhaust gas through the coil 3 by control of thevalve I5. The humidostat may effect control of the valve, {.5- by anyknown or desired means, the

connection between the humidostat and the valvebeingindicated by theline it.

Theoperation of the apparatus described above furthe. treatment oftobacco will, it is believed, be obvious. However, it will be noted thatthe humidostat and thermostat within the shed will: be set for theconditions desired for the curing of leaves of green tobacco y' hung inbanks on opposite sides of the free zone itil within the shed. Thetractor and air conditioning apparatus upon the trailer having beenconnected together as described above and the intake and eX- haustconduits of the conditioning apparatus having been moved into engagementwith the sideof the shed in alignment with the openings therein, thetractor engine will be started. In operation of the tractor engine, thefan 9 will be rotated and circulation of air into, within and out of theshed will be set up. The fan will be operated to deliver such quantityof air as to set up a positive pressure within the shed, which may bereadily accomplished due to introduction of the air in a `zone centrallyof the mass of tobacco, which will act to baille the passage of the airto the sides of the shed. The circulation within the shed will be suchas described and as shown by Figure 2. The closure u for the fresh airopening t will be adjusted, as will the louvers a to admit atmosphericair. The adjustment of the louvers and of the closure u will depend uponthe condition of the atmospheric air with respect to the conditiondesired in the shed and the direction or the wind. Variously during thecur-` ing period the louvers a may be entirely closed and variously whenthe curing has progressed the air conditioning.apparatus may be shutdown and. thecuring allowed to proceed under atmospheric air admittedthrough the louvers. rlhe air passing outwardly and downwardlyvbetweenthe banks of leaves will be deflected downwardly within the mass ofleaves by thev leaves as it progressesv outwardly.

Hot water from the water jacket of the tractor engine. will becirculated through the coil c, for

adjustment of the temperature of the air withdrawn fromv the shedtogether with the fresh air added thereto, by means of the pump Z. Theamountof circulation with reference to the heat of the water willbecontrolled by the thermostat i2, sov that the air willy be brought tothe desired temperature. As desired, hot exhaust gas from theA exhaustmanifold of the tractor engine will be circulated through thev coil 3for the evaporation. of water from( pan 2. The amount of gas passedthrough the coil 3- for the evaporation of such an amount of water fromthe pan 2 to bring ther air to the desired relative humidity will becontrolled by the valve l5, under control of the. humidostat i4.

Asv will be obvious, the air at desired relative humidity andtemperature willthen be returned to the shed forl curingif the louvers abe closed or if they be open more orV less to temper the atmospheric airentering through the louversfor the maintenance of desired conditionswithin the shed. Generally the outer portion of the mass of tobaccowillact to baille or hold the conditioned. air within the mass.

In many, iifnot all, instances, it will be desirable variously toutilize` the stack effectv aiorded by the ventilators Thus, when thecharging of the shedwith tobacco is. completed, it will usually` befound that air heated by the sun on the roof. has accumulated in theupper part of 'the shed and that the tobacco therein hasrstartedto.

with the tobacco in the upper. part of they shed,`

to the end that all the tobacco will beuniformly cured in the subsequenttreatment involving use of the conditioning apparatus and tion of air tocreate a positive` pressure within the shed. Air under positive`pressure within the shed may also be used variously during any stage ofthe curing when it is desired to heighten the stach eiiect. Such may beaccomplished by the introduction of atmospheric air into the shedthrough nozzles f in the preliminary stage, or conditioned air vhen thestach eiect is used in a subsequent stage of the curing.

Referring now more particularly to Figures 6 8, which illustrate certainmodifications of the showing ci Figures 1 5 and in which similar partsto those shown in Figures l-5 are indicated by similar symbols, withinthe upper part ofA the shed extending longitudinally thereof beheath tl?ridge oi the roof is a duct ll from which extend downwardly, at shortintervals in a zone extending vertically within the mass of tobaccosupported cn sticks 7c, vertical ducts 22 provided at intervals withlateral, slightly downwardly extending nous es and with dampers 6lproportioned to pass some air, say about 30%l when closed. The nozzles23 on one side ci the vertical ducts are desirably larger than those onthe other side, as shown. in Figure lil. l'helo-wer ends oi the ductsare closed by spring held flapper valves i543.

The vertical ducts extend downwardly inv the free Zone itil between thebanks of tobacco and are rotatably supported from the duct as forexample, through the medium of ball bearings (Figure il) and each of theducts is connected to a wind vane 5i, supported on the shed roof,through a 1:1 searing and a shaft 53 to which the wind vane is secured.Thus, the ducts 22 may be rotated, when there is sufficient wind forceoperating on the vane 5l, to various positions dependent upon the winddirections. The wind vane il will be arranged so that the largeropenings 3 will open against the wind.

Within each oi" the ducts is arranged a spiral ange lit (Figure ll)which, on the passage of sufficient air flow down the ducts 22, willcause the ducts to be rotated when the wind velocity is inconsequentialand as a consequence the vane 5i does not exert a directing eirect uponthe openings in the duct The duct E' is connected intermediate its endswith the discharge of the fan S by a duct M. The nozzles 23 are spacedso as to' project air from the ducts 32 in zone iii-il between the banksof tobacco over and downwardly upon the butts of the leaves of tobaccoj, j hanging from the sticks k, a downward circulation of the airthrough the tobacco leaves from the butts to their tips, as indicate thearrows Figure 6, being promoted by fan which draws air from the lowerpart of the shed through outlet opening o. The air in effect circulatesdownward in a plurality of layers or blankets so that the greatestamount of air is moving downward in the lower part of the shed. The airis. desirably introduced in amount the introducto create la positivepressure within the shed, which is made possible by insulating effect ofthe banks of tobacco.

Within the shed may be placed charcoal pots 24, or other heatingelements, which may be used when for any time in the curing of thetobacco a temperature higher than that obtainable with the airconditioning apparatus is desired and which, if burning, will increasethe stack effect resultant from the opening of ventilators 52 when suchis desired.

If desired, an auxiliary heating element til may be arranged within theintake duct p and may be controlled by thermostat I2.

In the air intake duct p of the conditioning apparatus, ahead of theheating coil v is a water spray head 25. The spray head 25 faces againstthe oW of air and is supplied with water by means of a pump 26 connectedto draw water, heated as desired, from pan 2. The air passing throughthe intake duct p receives water sprayed from the spray head 25 and onbeing heated in its'passage through coil v takes up a major portion ofthe water, any free water being thrown out of the air and returned'topan 2 as the air strikes the curved end of duct p in its passage to thedischarge duct r.

In the discharge duct'r adjacent to its point of discharge into thecasing of the fan 9 is placed a second water spray head 27 which, facingin the direction of the ow of air from duct 1' into the fan casing,discharges a spray of water into the fan casing for admixture vwith theair by the blades of the fan in the presence of the heat put into theair by the fan. The spray head 2'1 is supplied with water by a pump 2Swhich is arranged to draw water from the pan 2. A conduit 29 leads fromthe bottom of the ian casing to the pan 2 for the return of Water nottaken up by the air in the fan casing.

A diierential thermostat 3S is placed to operate on the differencebetween the temperature of the air entering the shed and that withdrawnand is connected by any suitable means 3l to control the throttle of thetractor engine W. The control by the thermostat will be such that whenthe temperature of the air withdrawn from the shed drops', the engineWill be speeded up, causf ing the fan to be speeded up, supplying morecirculation and heat to the coil '12 for heating the air in theconditioning apparatus. Thus, the thermostat 3U exercises control of thevolumeand `temperature of the air circulated in the shed.

Conversely, when'humidiiying without heating a differential humidostat3W operates to control the amount of moisture supplied to the shed byeiectin'g an lincrease or decrease in the rate of circulation throughconnection 3l' to the engine throttle.

In the operation of the modiiied form of apparatus shown in Figures 68,the procedure will lbe essentially the same as that described inconnection with the 'use of the apparatus shown in Figures 1-5. However,it will be noted by virtue of the arrangement of the air dischargenozzle 23, which discharges from the duct 22, `conditioned yairissupplied rst to the butts and stems of the nozzles 23 being properlyconditioned for treatment of the butts of the leaves becomes, by virtueof moisture absorbed from the butts and the cooling effect of the lossof moisture from the butts, proper for treatment of the median portion,and in turn for the tip portions. The downward circulation in which theair flows from butt to tip of the leaves insures that the air reachesthe median portion of the leaves between the leaves which -tend to beshielded from an upward flow of air by the form of the leaves as theyare strung in pairs and by the relatively greater breadth of this medianportion. Hence, rot which occurs on the shielded median portion isavoided.

By virtue of the directing effect of the wind ,vane 5|, if there be aWind of substantial velocity forcing air into the shed through the sidewalls, the ducts 22 will be positioned by the Wind vane with the largerof the openings 23 discharging into the wind. Hence, the effect ofexcessive wind velocity will be negatived by the larger volume of airdischarged against the wind as compared to with it. If the Wind velocitybe incon- .sequential the ducts 22 may be caused to rotate for averageuniform delivery of air to the tobacco by the action of the downiiowingair on the special iianges 54 in the ducts 22.

The introduction of Water into the air in the conditioning apparatusthrough spray head 25 and the introduction of a spray of water into thefan casing insures the proper humidication of the air in conjunctionwith the water supplied to the air by vaporization from tank 2.

When the shed is initially loaded with cold, relatively wet tobacco andhigher than average heat is required, suiiicient air is delivered toducts 22 to cause the valves 60 at their lower ends to open, thuspermitting the delivery of an increased quantity of air into the shed.

It will be noted that the temperature of the air circulated through theshed will be fixed by the heat supplied to the air in passing over coilv and also by the heat put into the air in its circulation, as by theWork done by the fan, friction in the clucts, etc., and by heatingelement 40, if desire As more specifically illustrative of procedureaccording to the method of this invention for the curing of greentobacco with the use of apparatus herein described and the operation ofwhich has been herein described in a general way, for example, it may beassumed that the shed A has been fully charged with green tobacco.

When the shed is fully charged with tobacco, it 'will be round generallythat curing of the tobacco 1n the upper part has commenced, While thetobacco in the lower part of the shed has not commenced to cure. Thissituation arises from the fact that the tobacco is charged into theupper part oi' the shed rirst, and due to the fact that the air in theupper part or the shed is hotter than that in the lower part of the sheddue variously to the heating effect of the sun on the roof.

Hence, in general, it will be desirable initially to open damper 63 andpermit a stack effect upon the interior of the shed through theventilator 62, while introducing air into the lower part oi' the shed toincrease the stack effect. If the air .introduced is warm, radiationfrom the surface of duct E will increase the stack eect.

The introduction of the air into the lower part of the shed incombination with the stack elect through the ventilator 62 will tend tohold the condition of, or slow down the curing process of the tobacco inthe upper part of the shed, while the tobacco in the lower partof theshed is being brought into condition `comparable with that of thetobacco in the upper part 'of the shed.

When using the apparatus shown, for example, in Figure 2, an amount ofair will be introduced 5 into the lower part of the shed through thenozzles and in such condition vas to primarilyaiect the tobacco in thelower part 'of the shed. When using the apparatus as shown in Figure 6the damper iii in the vertical conduit 23 will be opened Yso that themajor portion of the air will pass down the conduit fordischargethrough'the nozzles 23 Yin the 'lower part of the shed.

The mass of tobacco as a whole in 'the shed having been brought to 'ar'substantialiy uniform state of curing, air wiii be `introduced throughthe nozzles f, Figure 2 or through the nozzles 2.5i, Figure 6, in thelatter cese with lthe iii adjusted for uniform discharge 'of air. Theair will, of course, be conditioned as has 'been indicated to promotethe Ydesired curing of "the tebacco. 'During the curing,'andespecially'diiring the second to sixth days, when part 'of the -leafcells are dead and part are still throwing "off moisture, the updraft'stack effect 'vviil 'be desirably used to carry off the evaporating'moisture to avoid the formatio'n'of bea-ds of sweat''n the leaves withconsequent promotion of attack by fungus.

During the treatment the 'louvers a 'will be opened to lcreate acirculation of atmospheric air to the extent indicated by conditionswithin the shed and by the precise condition to be maintained within theshed.

A lpositive lpressure Within the 'shed will be readily obtained byvirtueof the insulating effect i the banks of tobacco on'opposite 'sidesof the shed. By virtue ofthe positive pressure within the shed the "airwill flow outwardly from VZone lh? as well Yas downwardly with respect"to "the tobacco -in the 'banks 'and 'the leaves the interior andthroughout themass wiil "thus besubjected to substantially 4uniformtreatment.

Since the tobacco `in the upperlpartof theblied will tend variously tolose `a greater amount 'of moisture than will the tobacco in the lou/.jrpa'rt of the shed, it may,'and usually wiil, bedesirable on the iifth orysixth -day of treatment to intro"- duce `a greater lquantity of air"having an in'- oreased moisture content 'into'the upper parte'c theshed than Ainto the lower part 'of the s by adjustment ofthe damper '6iin the vertical conduit 22. Under such condition the'dam'per 6:5 andventilator e2 maybe uclosedor adjusted to give more or less stasi;eiiect and,'depending upon conditions, the llouvers u' may be-ciosedormore or less opened. variously the tobacco 'in the upper part of theshed may lose moisture more rapidly than that in 'the iower part" duetothe effect oi" the suns -heat `on the shed roof. In such case cool,moist evening air maybe intro-duced into the upper part of the 'shedthrough theventilator by causing-a dovvndraftbyselecu tively dischargingcool, -moist air 'into the upper part of the shed and by the'coolingefect of duct E and ducts 272, through which the Vcool air isintroduced. l

It will be yappreciated that stack effect`obtained by use of theventilator iiand the int duction of air in varying amount in the 'upperor lower portion of the liree zone iiiiiythe creation of a positivepressure within the shed, the use of the louvers `aand of theconditioningl apparatus for the-air supplied "from zone VHit 'willenable the mass of tobacco within theshed'to'b'e f;

subjected to substantially uniform ideal condii tions for its curing,with avoidance of pole sweating and other negative eiects on its color,texture and davor, and with reference vto the curing process as a whole.it will also be appreciated that by virtue of vertical draft up or downprovided for, atmospheric air will be introduced into the shed, sincethe ventilator and louvers will be of suiiifient size, to supplement theair from the conditioning apparatus, thus enabling good curing to beobtained with the use of a minimum of power and equipment.

The advantage of the method in accordance with this invention will, itis believed, be apparent. The apparatus, exempliiied for Carrying outthe method, is of the greatest simpieit-y and for its operation andtransportation from place to place requires only an ordinary farmtractor and the curing of green tobacco is enabled with accuracy ofcontrol with consideration for the changing condition of the tobacco inthe course of curing and changes in the condition of outside atmosphereand of wind direction and 'velocity. At the same time, favorableatmospheric conditions are utilized in the usual Way when they exist.

lt will be understood that the method above disclosed and variously thedetails thereof are not limited in their application to the drying oftobacco, but variously are adapted for application to the moistening oftobacco, in which application they variously are of advantage.

It will be appreciated that it is not intended to limit this inventionby the above detailed description given for illustrative purposes,since, c

as will be obvious, various modification in detail may be made withoutdeparting from the scope of the invention.

This application is a continuation-impart of the application led by ineSerial No.274,133, viled May l?, 1939, which application becameabandoned December l2, 194i).y

What I claim Yand desire to protect -by Letters Patentis: n

1. The method of curing green tobacco leaves after harvesting whichcomprises supporting Ygreen tobacco lleaves vin superimposed banks, `op-.posite ends of the banks being exposed to V'atmospheric air andadjacent endsof the banks being separated to form a free zone andcausing conditioned air from said free Zone at a posi- Vtive pressuretherein to ow laterally Youtwardly ninto the banks of tobacco leaveswhereby `thetovbacco'leaves in the opposite end portions ofthe bankswill be'cured by atmospheric air `and the tobacco Yleaves in thera'djacentjend 'portions of the banks will beoured by conditionedair.

2. The method of curing green tobacco vleen/es after harvesting whichcomprises supporting the green tobacco leaves'in a mass in a pendentposition ina chamber, setting up a v`ciowoioonditioned air fromwithinthe mass of tobaccd'latverally and downwardly 'over'thetobacod "frombutt to tip of the leaves, withdrawingair from nsaidchambcryconditioning the air with respect to temperature andy humidityand' returning git" to said chamber for reflow therein 'and eiecting theadmission of atmospheric air atthesidesof themass. Y Y

3. The method of curingg'reen tobacco leaves after'harvesting whichcomprises supportinghe "green tobacco leaves in' a chamben'inbanksih 'amass in a pendentfposition, iiowin'g"`conditined fair from within themass, at *a vr{ io'sitive "preslsure, outwardly and downwardly between"the banks of leaves, admitting atmospheric air to the chamber through apair of opposite walls thereof and flowing conditioned air into thelower part of the chamber beneath the banks of leaves.

4. The method of curing green tobacco leaves after harvesting whichcomprises supporting the green tobacco leaves in a chamber in banks in amass and in a pendent position and projecting streams of conditioned airof alternately varying volume laterally and downwardly between the banksof leaves.

5. The method of curing green tobacco leaves after harvesting whichcomprises supporting green tobacco leaves in a mass in a pendentposition in a chamber and introducing air under pressure laterally onlyinto that portion of the mass of tobacco leaves which is supported inthe lower part of the chamber and at the same time withdrawing air fromthe lower part of the chamber with stratication in the lower part of thechamber of air introduced into the lower part of the chamber.

6. The method of curing green tobacco leaves after harvesting whichcomprises supporting green tobacco leaves in a mass in a pendentposition in a chamber having an opening to the atmosphere in one of itswalls, introducing conditioned air under pressure to the tobaccolaterally only from a zone extending vertically within the mass oftobacco leaves and permitting exhaust of air from the top of thechamber, whereby the conditioned air introduced into the chamber will besupplemented by atmospheric air from without the chamber.

7. The method of curing green tobacco leaves after harvesting whichcomprises supporting green tobacco leaves in a mass in a pendentposition in a chamber, introducing air from a zone within the masslaterally into that portion of the mass of tobacco leaves which issupported in the upper part of the chamber and at the same timewithdrawing air from the upper part of the chamber with stratificationin the upper part of the chamber of air introduced into the upper partof the chamber.

3. The method of curing green tobacco leaves after harvesting whichcomprises supporting green tobacco leaves in a mass in a pendentposition in a chamber, introducing cool air from a zone within the masslaterally into that portion of the mass of tobacco leaves which issupported in the upper part of the chamber only and at the same timewithdrawing air from the upper part of the chamber with stratificationin the upper part of the chamber of air introduced into the upper partof the chamber.

9. The method of curing green tobacco leaves after harvesting whichcomprises supporting the green tobacco leaves in a chamber, in banks ina mass in a pendent position and flowing conditioned air from the centerof the mass outwardly and downwardly between the banks of leaves whileadmitting atmospheric air to the chamber through a pair of oppositewalls thereof, thei stantially uniform state of curing, then introducingair into the mass of tobacco laterally from a zone extending verticallywithin the mass of tobacco to effect its curing.

11. The method of curing green tobacco leaves after harvesting whichcomprises supporting green tobacco leaves in a mass in a pendentposition in a chamber, introducing air into the lower part of thechamber only and affording escape for air from the upper part of thechamber until the tobacco in the chamber is at a substantially uniformstate of curing, then introducing air into the mass of tobacco laterallyfrom a zone extending vertically within the mass of tobacco to eect itscuring and in the course of the curing affording an escape for air fromthe upper part of the chamber and admitting atmospheric air through apair of opposite walls of the chamber.

12. The method of curing green tobacco leaves after harvesting whichcomprises supporting green tobacco leaves in a mass in a pendentposition in a chamber, introducing air into the lower part of thechamber only and affording an escape for air from the upper part of thechamber until the tobacco in the chamber is at a substantially uniformstate of curing, then introducing air into the mass of tobacco laterallyfrom a zone extending vertically within the mass of tobacco to eiect itscuring and in the course of the curing allording an escape for air fromthe upper part of the chamber, admitting atmospheric air through a pairof opposite walls of the chamber and introducing into the upper part ofthe chamber air having a moisture content greater than that of the airintroduced into the lower part of the chamber.

13. The method of curing green tobacco leaves after harvesting whichcomprises supporting green tobacco leaves in a chamber in a pendentposition in a mass, subjecting vertical exterior portions of the massdirectly to atmospheric air and, at the same time, introducingconditioned air under forced flow interiorly of the mass to produce andmaintain a positive pressure within the mass to promote a flow ofconditioned air laterally in the mass whereby tobacco leaves in exteriorportions of the mass will be treated essentially by atmospheric air andtobacco leaves in interior portions of the mass will be treatedessentially by conditioned air.

14. The method of curing green tobacco leaves after harvesting whichcomprises supporting green tobacco leaves in a chamber in a pendentposition in a mass, subjecting vertical exterior portions or the massdirectly to atmospheric air and, at the same time, directing conditionedair under forced flow interiorly of the mass to produce and maintainpositive pressure Within the mass to promote a flow of conditioned airlaterally in the mass, whereby tobacco leaves in exterior portions ofthe mass will be treated essentially by atmospheric air and tobaccoleaves in interior portions of the mass will be treated essentially bconditioned air.

l5. The method of curing green tobacco leaves after harvesting whichcomprises supporting green tobacco leaves in a chamber in a pendentposition in a mass, subjecting vertical exterior portions of the massdirectly to atmospheric air and, during the curing of the mass,directing conditioned air under forced flow interiorly of the mass toproduce and maintain positive pressure within the mass to promote a owof conditioned a-irlaterllydn the mass, whereby tofoaocefleegfes lin'exterior portions of the :nase will beftreated essentially'oyatmospheric air and'tobeiccofleaves in interim` portionsof the Will/hetreated Vessentially by conditioned air.

1'16. The methodof curing green tobacco leaves vafter harvesting whichcomprises supporting 'green tobacco lea-ves in a mass in apendentposition in a Chamber, introducing air under Vpressu're'to a,portion of the mass 'of tobacco laterally lorilyrom a Zone extendingvertically Wit'hin'the y1'1'i`a3ss of 'tobacco leaves 4While permittingYexhaust 'of ali'r from 'the upper portion of the chamber.

Uafter harvesting :17. 'hemetho of curing'greentobacco-leaves whichcomprises supporting green tobacco leaves ina mass in'aperiden'tpos'ition in a chamber 'and in reducing 'heated 5air underpressure laterally only into that portion of the mass-of `tobacco leaveswhich `is Supported in

